[Bug tree-optimization/69801] New: gcc ICE on valid code on x86_64-linux-gnu in "operand_equal_p"

[helloqirun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69801

            Bug ID: 69801
           Summary: gcc ICE  on valid code on x86_64-linux-gnu in
                    "operand_equal_p"
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: helloqirun at gmail dot com
  Target Milestone: ---

The following valid code causes an ICE when compiled with the current gcc trunk
on x86_64-linux-gnu in both 32-bit and 64-bit modes.



(*) But a nearly identical case can pass.



$ gcc-trunk  -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/home/absozero/trunk/root-gcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/home/absozero/trunk/root-gcc
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 6.0.0 20160212 (experimental) [trunk revision 233377] (GCC)



$ gcc-trunk abc.c -c
abc.c: In function 'fn1':
abc.c:5:1: internal compiler error: in operand_equal_p, at fold-const.c:2776
 void fn1() { e ? (d ? b : c).c : (d ? b : c).c; }
 ^~~~
0x872dc5 operand_equal_p(tree_node const*, tree_node const*, unsigned int)
        ../../gcc/gcc/fold-const.c:2776
0x871c2e operand_equal_p(tree_node const*, tree_node const*, unsigned int)
        ../../gcc/gcc/fold-const.c:2982
0x872378 operand_equal_p(tree_node const*, tree_node const*, unsigned int)
        ../../gcc/gcc/fold-const.c:3123
0x8714c6 operand_equal_p(tree_node const*, tree_node const*, unsigned int)
        ../../gcc/gcc/fold-const.c:3067
0x8711ca operand_equal_p(tree_node const*, tree_node const*, unsigned int)
        ../../gcc/gcc/fold-const.c:3091
0xf5ff61 generic_simplify_COND_EXPR
        /home/absozero/trunk/build-gcc/gcc/generic-match.c:26035
0xf5ff61 generic_simplify(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*, tree_node*)
        /home/absozero/trunk/build-gcc/gcc/generic-match.c:26273
0x87e93c fold_ternary_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*, tree_node*)
        ../../gcc/gcc/fold-const.c:11406
0x880ee3 fold_build3_stat_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*, tree_node*)
        ../../gcc/gcc/fold-const.c:12506
0x68b7e3 c_fully_fold_internal
        ../../gcc/gcc/c/c-fold.c:506
0x68cd4b c_fully_fold(tree_node*, bool, bool*)
        ../../gcc/gcc/c/c-fold.c:90
0x629a0f c_process_expr_stmt(unsigned int, tree_node*)
        ../../gcc/gcc/c/c-typeck.c:10231
0x629e0d c_finish_expr_stmt(unsigned int, tree_node*)
        ../../gcc/gcc/c/c-typeck.c:10276
0x6770d0 c_parser_statement_after_labels
        ../../gcc/gcc/c/c-parser.c:5275
0x678d5b c_parser_compound_statement_nostart
        ../../gcc/gcc/c/c-parser.c:4859
0x6795de c_parser_compound_statement
        ../../gcc/gcc/c/c-parser.c:4695
0x675144 c_parser_declaration_or_fndef
        ../../gcc/gcc/c/c-parser.c:2107
0x68089d c_parser_external_declaration
        ../../gcc/gcc/c/c-parser.c:1551
0x6812c9 c_parser_translation_unit
        ../../gcc/gcc/c/c-parser.c:1429
0x6812c9 c_parse_file()
        ../../gcc/gcc/c/c-parser.c:17826
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.



$ cat abc.c
struct {
  char c[1];
} b, c;
int d, e;
void fn1() { e ? (d ? b : c).c : (d ? b : c).c; }



A nearly identical case:
$ diff abc.c a.c
5c5
< void fn1() { e ? (d ? b : c).c : (d ? b : c).c; }
---
> void fn1() { e ? (d ? b : c).c : (e ? b : c).c; }

$ gcc-trunk a.c -c

Syntactically, variables d and e should be treated in the same way.